To determine whether, on a background of optimal medical therapy with low-dose ASA and ticagrelor, a strategy of complete revascularization involving staged PCI using drug eluting stents of all suitable non-infarct related artery lesions is superior to a strategy of culprit lesion-only revascularization in reducing the composite outcome of CV death or MI in patients with multi-vessel disease who have undergone successful culprit lesion primary PCI for STEMI.